1. Field of the Invention
The present invention relates to an automatic document transportation device in a scanner, a facsimile machine and a copy machine or the like, which transports an original document on a document tray through a transportation path to a scanning position and a document discharge tray.
2. Description of the Related Art
A scanner, a facsimile machine and a copy machine or the like each includes an automatic document transportation device having an Automatic Document Feeder (ADF) which sequentially feeds a plurality of original documents. By using the automatic document transportation device, a plurality of original documents placed on a document tray can be transported continuously and automatically to a scanning position.
FIG. 12 is a schematic perspective view showing an exterior of a copy-and-facsimile Multi Function Peripheral (MFP) 900 having the ADF. As shown in the drawing, the copy-and-facsimile MFP 900 includes a scanning table 901, a document pressing cover 902, an operation panel 903, a frame 904 and paper feed cassettes 905. The scanning table 901 includes a platen glass on which an original document to be scanned is placed. The document pressing cover 902 presses and fixes the original document on the platen glass. The operation panel 903 is used for, for example, inputting a start of a scanning process of the original document. The frame 904 includes an image printing unit which prints an image onto recording paper and a transmission unit which electrically transmits the image, or the like. The paper feed cassettes 905 feed recording papers for printing the scanned image. In the copy-and-facsimile MFP 900, the automatic document transportation device is formed by the ADF in the document pressing cover 902. An original document on a document tray 906 is transported by the ADF from the document tray 906 to a document discharge tray 907 provided below the document tray 906, from an upper side to a lower side in a U-turn manner. In the transportation process, when the original document passes the scanning position on the platen glass, an image of the original document is scanned by the image scanning unit such as a Charge Coupled Device (CCD) provided in the scanning table 901.
FIG. 13 is a cross-sectional view showing a schematic configuration of the document pressing cover 902 of the copy-and-facsimile MFP 900. As shown in the drawing, a transportation path 908 is formed from the document tray 906 via an image scanning surface to the document discharge tray 907. The original documents on the document tray 906 are transported continuously to the document discharge tray 907 by a document feed roller 909 provided in proximity to an inlet of the transportation path 908 and transportation rollers 910 provided appropriately along the transportation path 908. When the original document picked up from the document tray 906 and fed into the transportation path 908 passes a scanning position P1 in the transportation process, an image scanning process is executed on one side of the original document by a scanning unit 911 such as a CCD provided in the scanning table 901. At a scanning position P2 located downstream of the scanning position P1, an image scanning process is executed on another side of the original document by a scanning unit 912 such as a Contact Image Sensor (CIS) provided in the document pressing cover 902.
In the above-described copy-and-facsimile MFP 900, when a user places an original document on the document tray 906 vigorously in a direction toward the transportation path 908, there are cases in which a leading edge of the original document collides against the document feed roller 909 and the original document is damaged. There are also cases in which leading edges of a plurality of original documents are caught by the document feed roller 909 and a multi-feeding is generated. To prevent such failures, there is a proposal made to provide a shutter 913 upstream of the document feed roller 909 in a manner that the shutter 913 can protrude and recede. When placing an original document on the document tray 906, the shutter 913 protrudes to shut the transportation path 908 for preventing the original document from entering downstream of the shutter 913. When transporting the original document, the shutter 913 recedes to permit the original document to pass through the transportation path 908.
Meanwhile, in the above-described copy-and-facsimile MFP 900, for carrying out maintenance work and for removing jammed paper, a cover is provided so that a housing of the document pressing cover 902 can be opened and closed. However, when the shutter 913 is provided on the cover, in case the cover is opened with the shutter 913 protruding, the original documents on the document tray 906, which were restricted by the shutter 913, flow into the transportation path 908. Then, when the cover is closed, the shutter 913 thrusts into the original documents and the original documents are damaged.